Effect of exercise-induced muscle damage on vascular function and skeletal muscle microvascular deoxygenation

This paper investigated the effects of unaccustomed eccentric exercise-induced muscle damage (EIMD) on macro- and microvascular function. We tested the hypotheses that resting local and systemic endothelial-dependent flow-mediated dilation (FMD) and microvascular reactivity would decrease, V˙O2max would be altered, and that during ramp exercise, peripheral O₂ extraction, evaluated via near-infrared-derived spectroscopy (NIRS) derived deoxygenated hemoglobin + myoglobin ([HHb]), would be distorted following EIMD In 13 participants, measurements were performed prior to (Pre) and 48 h after a bout of knee extensor eccentric exercise designed to elicit localized muscle damage (Post). Flow-mediated dilation and postocclusive reactive hyperemic responses measured in the superficial femoral artery served as a measurement of local vascular function relative to the damaged tissue, while the brachial artery served as an index of nonlocal, systemic, vascular function. During ramp-incremental exercise on a cycle ergometer, [HHb] and tissue saturation (TSI%) in the m. vastus lateralis were measured. Superficial femoral artery FMD significantly decreased following EIMD (pre 6.75 ± 3.89%; post 4.01 ± 2.90%; P < 0.05), while brachial artery FMD showed no change. The [HHb] and TSI% amplitudes were not different following EIMD ([HHb]: pre, 16.9 ± 4.7; post 17.7 ± 4.9; TSI%: pre, 71.0 ± 19.7; post 71.0 ± 19.7; all P > 0.05). At each progressive increase in workload (i.e., 0-100% peak), the [HHb] and TOI% responses were similar pre- and 48 h post-EIMD (P > 0.05). Additionally, V˙O2max was similar at pre- (3.0 ± 0.67 L min^-1) to 48 h post (2.96 ± 0.60 L min^-1)-EIMD (P > 0.05). Results suggest that moderate eccentric muscle damage leads to impaired local, but not systemic, macrovascular dysfunction.